Infrared asphalt heating apparatus and method

ABSTRACT

An infrared asphalt heating and repair apparatus includes a converter having downward facing slits cut therein to provide enhanced durability over prior art ceramic blanket or metal ribbon style heaters. In embodiments, the slits are cut by a milling machine, which may be an automatic milling machine, a band saw, or a laser. Embodiments also provide for more uniform heating over prior art solutions, while largely preventing damaging and costly flame-through events. Because the heat is more uniform than that of the prior art, lower temperatures can be used to achieve similar results, thereby extending equipment life, lowering fuel costs, and reducing warm-up times.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/906,552, filed on Nov. 20, 2013. This application is hereinincorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to asphalt repair, and more particularly, toinfrared heating and repair of asphalt.

BACKGROUND OF THE INVENTION

Asphalt is in use in most places that vehicles are. Asphalt is durable,economical, and should last for many years. Asphalt will not lastforever though, and some sections of asphalt may well deteriorateprematurely, leading to failure of surrounding portions if not addressedpromptly. Common causes of premature failure in asphalt sections areexcessive water flow, poor drainage, sinking of underlying ground, andoil, grease, gasoline, or chemical oxidation.

The United States alone spends roughly $16 billion USD annually onrepair of existing roadways (calculated based on the Federal HighwayAdministration's Highway Statistical Series, for years 2004-2008).According to the American Association of State Highway andTransportation Officials, every $1 spent to keep a road in goodcondition avoids $6-14 needed later to rebuild the same road once it hasdeteriorated significantly (American Association of State Highway andTransportation Officials (AASHTO) and The Road Information Project.(2009). “Rough Roads Ahead: Fix Them Now or Pay for It Later.”http://roughroads.transportation.org/.)

To this end, many repair techniques have been developed, such as“throw-and-go” (placing fresh asphalt into a pothole or crack, with nofurther steps), “throw-and-roll” (similar to throw-and-go, but alsoincludes an attempt to compact the fresh asphalt by driving over it witha vehicle), spray injection (requires customized vehicles and materials,involves spraying of asphalt mix through a nozzle and onto the existingasphalt to be repaired), edge seal (cutting the deteriorated pavementout, adding fresh asphalt, and compacting with vibratory rollers or thelike), and infrared heating and repair. Of these, infrared heating andrepair of damaged asphalt has many benefits, including seamless bondingof the patch to the surrounding asphalt, requiring only one trip to thesite of the repair, less new asphalt being necessary to make a similarrepair, fewer freeze/thaw issues occurring, and less potential forinjury of workers, because there is no need for saw cutting, jackhammering, spraying of solvents, or the like.

Existing infrared asphalt repair apparatus are either of the ceramicblanket or metal ribbon variety. Ceramic blanket heaters typical of theprior art use LPG (Liquefied Petroleum Gas) to heat a ceramic blanket,which in turn radiates infrared energy. Metal ribbon heaters generallyuse a plurality of thin strips (ribbons) of metal that are placed in achannel, bent in a wave-like pattern, and welded every 6-12″. LPG ischanneled through the orifices formed between the metal ribbons, andlit. This LPG then heats grids, typically made of nickel chromium, whichradiate infrared energy into the pavement. Infrared heating is usedinstead of purely convective heating due to superior efficiency. Byusing infrared radiation, less heat is wasted heating up the surroundingair, because the infrared radiation travels through the air, losinglittle energy, before being absorbed by the asphalt. Infrared heatingalso provides quicker heating of sub-surface asphalt than purelyconvective heating. Because the actual heating is done through infraredradiation, rather than convective heating, the asphalt is evenly heatedand softened throughout its depth. However, the current state of the artin infrared heating and repair of asphalt is not without its problems.

Ceramic blanket heaters will eventually need to have the ceramic blanketreplaced at substantial cost, either due to normal use or because it hasdeveloped tears in the material. The efficiency of ceramic blanketheaters will also deteriorate because of a buildup of carbon and othercombustion byproducts on the ceramic blanket over time.

Metal ribbon infrared asphalt heating and repair devices also sufferissues that prevent their widespread adoption, typically suffering fromuneven and inconsistent heating, unreliable operation, high temperatureoperation (reduced durability), and high fuel usage. In particular, thesizes of the orifices created by bending and periodically welding metalribbon material in a channel are inconsistent, in turn affecting theuniformity of heat given off by the device. This variation in orificesize and heat requires additional expenditure of fuel to achieve atleast a minimum usage temperature throughout the heated region, and alsoallows for occasional large bursts of flame through these ribbons,referred to as flame-throughs, which can cause failure of the nickelchromium grids, as well as scorching of the asphalt. The higher thannecessary operating temperature required because of the non-uniformoutput of these devices also considerably shortens the life of thenickel chromium material.

What is needed, therefore, are apparatus for infrared heating and repairof pavement that use less fuel, eliminate flame-through events, providemore uniform output, and are more robust than those of the prior art.

SUMMARY OF THE INVENTION

One general aspect of the present invention is an infrared asphaltheating and softening system for infrared repair of asphalt, comprisingat least one blower operatively connected to a fuel supplying conduit,at least one manifold, fixed to a frame, in communication with the fuelsupplying conduit, at least one converter, which may, in embodiments, beof a cylindrical shape and made of stainless steel, in fuelcommunication with said manifold and having a plurality of downwardfacing slits through which fuel can emerge and combust, the converterbeing positioned within the frame, at least one reflector configured toreflect infrared radiation produced by the converter downwardly, and atleast one grid, made of infrared emitting material, configured such thata combustion chamber is formed between the converter and the grid, thegrid further configured to absorb heat produced in the combustionchamber and re-emit the heat downwardly in the form of infraredradiation.

Another embodiment of the present disclosure provides such an infraredasphalt heating and softening system wherein the downward facing slitsof the converters, which may be made of stainless steel and cylindricalin shape, are approximately 0.4688″-0.5000″ wide. These slits may alsobe between approximately 0.025″-0.035″ thick.

Yet another embodiment of the present invention provides such aninfrared asphalt heating and softening system for infrared asphaltrepair wherein the downward facing slits of the at least one converternumber 64 slits per 34″ of converter length.

Still another embodiment of the present invention provides such aninfrared asphalt heating and softening system wherein the aforementionedgrid is made of nickel chromium.

A still further embodiment of the present invention provides such aninfrared asphalt heating and softening system wherein said the at leastone reflector is made using stainless steel.

Even another embodiment of the present invention provides such aninfrared asphalt heating and softening system wherein a first slit and alast slit are positioned 1.250″ from opposing ends of the converter.

An even further embodiment of the present invention provides such aninfrared asphalt heating and softening system wherein the plurality ofdownward facing slits are produced using a milling machine.

A still even further embodiment of the present invention provides suchan infrared asphalt heating and softening system wherein the pluralityof downward facing slits are produced using a band saw.

A still yet even further embodiment of the present invention providessuch an infrared asphalt heating and softening system wherein theplurality of downward facing slits are produced using a laser.

Another general aspect of the present invention is a method for infraredrepair of asphalt, comprising providing an infrared asphalt heating andsoftening system including at least one blower operatively connected toa fuel supplying conduit, a manifold, fixed to a frame, in communicationwith the fuel supplying conduit, at least one converter in fuelcommunication with the manifold and having a plurality of downwardfacing slits through which the fuel can emerge and combust, theconverter being positioned within the frame, at least one reflectorconfigured to reflect infrared radiation produced by the converterdownwardly, toward asphalt to be repaired, and at least one grid, madeof infrared emitting material, configured to absorb heat produced by theconverter and re-emit the heat toward the asphalt as infrared radiation,heating an area of asphalt to be repaired using the infrared asphaltheating and softening system until it is soft enough to be scarifiedusing hand tools; scarifying and repositioning the softened asphalt,smoothing the softened asphalt, and adding fresh asphalt over thesmoothed asphalt.

Another embodiment of the present invention provides such a method,further comprising compacting the fresh asphalt.

Yet another embodiment of the present invention provides such a method,wherein compacting of the fresh asphalt is accomplished using avibratory compactor.

A yet further embodiment of the present invention provides such amethod, wherein compacting of the fresh asphalt is accomplished usingcompaction equipment selected from the group consisting of paverscreeds, steel wheel rollers, and pneumatic tire rollers.

A still further embodiment of the present invention provides such amethod, further comprising adding maltenes to the heated and scarifiedasphalt prior to smoothing. Additional embodiments also add asphalteneswith the maltenes.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and not to limit the scope ofthe inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom elevation view of one embodiment of the infraredpavement repair apparatus of the present disclosure;

FIG. 2 is a front, top, right-side perspective view of an infraredpavement repair apparatus in accordance with one embodiment of thepresent disclosure;

FIG. 3 is a bottom elevation view of a converter, specifically a bottomconverter, in accordance with one embodiment of the present disclosure;

FIG. 4 is a left-side elevation view of a converter, specifically a topconverter, in accordance with one embodiment of the present disclosure;

FIG. 5 is a bottom elevation view of assembled top and bottom converterswith reflectors, in accordance with one embodiment of the presentdisclosure;

FIG. 6A is a bottom elevation view of a converter, in accordance withone embodiment of the present disclosure;

FIG. 6B is a section view showing the slit shape used in a converter, inaccordance with one embodiment of the present disclosure;

FIG. 7 is a top, front, right-side perspective view of, from left toright, respectively, a left-reflector, center reflector and rightreflector, in accordance with one embodiment of the present disclosure;

FIG. 8 is a right-side elevation view of a grid used for generation ofinfrared energy, in accordance with one embodiment of the presentdisclosure;

FIG. 9 is a detail view of the grid of FIG. 8, in accordance with oneembodiment of the present disclosure;

FIG. 10 is a top, rear, right-side perspective view of a frame andsubassemblies which comprise an infrared asphalt repair apparatus, inaccordance with one embodiment of the present disclosure; and

FIG. 11 is a bottom, rear, left-side perspective view of a frame andsubassemblies which comprise an infrared asphalt repair apparatus, inaccordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present invention provide precisely slottedtube-style converter assemblies, which can be manufactured to tightertolerances, in lieu of prior art ribbon or ceramic blanket assemblies,producing a more consistent converter orifice size and a more robustapparatus.

Due to the more consistent sizes of the converter orifices, flameheating is produced more uniformly over the entire heated area ascompared to the prior art ribbon converters, so that lower averageoperating temperatures are required. This leads to reduced fuelconsumption and enhanced durability of the asphalt repair equipment.

One embodiment of an infrared asphalt heating apparatus in accordancewith the present disclosure is illustrated in FIGS. 1 and 2. Thisembodiment may use multiple fuel connections 100, each in communicationwith fuel supply manifolds 105, which are in further communication withconverters 115, which may be beneficially attached through the use ofpipe fittings 110, although many other types of fittings may also beused. The number of converters 115, fuel connections 100 and fuel supplymanifolds 105 is scalable, in embodiments, and may be as few or as manyas is necessary to expeditiously complete the repair task at hand.Reflectors 120 are also shown, which act to focus infrared radiation,produced by combustion of fuel in the converters 115 and subsequentheating of a specially designed grid 800 (not shown in FIG. 1 or 2),into asphalt to be repaired when the apparatus is in operation.

The converters 115 may be secured to a frame 905 (shown in FIG. 10), asis described in more detail below with reference to FIGS. 10 and 11,using provided tabs 125, which include connection points 405, asdiscussed in more detail below with reference to FIG. 4. Rivets, bolts,welding and other methods of fastening the converters to a frame 905 ofsuitable size given the intended repair task may also be utilized.

As best illustrated in FIG. 5, some embodiments of the present inventionutilize interconnect-able converters 115, allowing for the apparatus tobe scaled to the project at hand while minimizing the size of shippedcomponents and the need to manufacture differently sized components.While embodiments of the distinct converters 115 utilize similar slit315 patterns and designs, hardware for the interconnection of convertersdiffers, dependent on the desired position of the converter in its frame905, as is described in more detail below with reference to FIGS. 3, 4and 5.

Now referring to FIG. 3, bottom converter assemblies 300, according tothe embodiment depicted may utilize pipe nipples 305 for connection to apipe fitting 110, in operative communication with a fuel supply manifold105, in addition to providing a plain pipe nipple 310 on an oppositeend, which may be used for interconnection with a top converter assembly400, as shown in FIG. 4.

The top converter 400 of FIG. 4, in embodiments, includes a tab 125 forsecuring the top converter assembly 400 to the apparatus frame 905. Thetab may be secured by welding in some embodiments to a converter 115including slits 315 to provide a top converter 400. Reflectors 120,including slots 700 for holding infrared emitting grids 800, may also beattached.

FIG. 5 illustrates one embodiment of the present invention, wherein abottom converter assembly 300 is operatively connected to a topconverter assembly 400 through use of a plain pipe nipple connection310.

FIGS. 6A and 6B illustrate a converter 115 with slits 315 configured inaccordance with one embodiment of the present invention. These slits maybe cut into the material using a variety of techniques and at a varietyof different sizes, however, use of a band-saw or other tool providing asimilar profile cut, with the cut itself having measuring between0.4688″-0.5000″ in width, has been shown to produce a desirable flamespread suitable for asphalt repair. In embodiments, slits 315 may beproduced in a converter 115 through use of a milling machine and afixture. These slots may desirably be 0.025″ thick to achieve optimalflame spread and energy transfer to the infrared emitting grid 800.

Other embodiments of the present invention may have slits 315 cut with alaser, a band saw, a milling machine, or a variety of other means, toachieve alternative flame spread patterns, which may be beneficial forspecific uses.

Reflectors 120 used in embodiments of the present invention can be madefrom sheet metal or similar material. Construction of embodiments of thepresent invention includes producing slots 700 in the reflector materialsuitable for holding infrared emitting grids 800 in place. Embodimentsof such grids 800 are fastened to the reflectors via grid legs 805 asshown in FIG. 8.

In embodiments, a dual 12 volt blower system 200 may be used to providean optimal air/fuel mix to the converters 115. The fuel may be liquidpetroleum gas (LPG), propane, or any of a number of liquid or gaseousfuels.

Various embodiments of the present invention use nickel chromium as theinfrared radiation emitting grid 700 material, as well as for theconverters 115 themselves.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. Each andevery page of this submission, and all contents thereon, howevercharacterized, identified, or numbered, is considered a substantive partof this application for all purposes, irrespective of form or placementwithin the application. This specification is not intended to beexhaustive or to limit the invention to the precise form disclosed.

Among that which is claimed is:
 1. An infrared asphalt heating andsoftening system for infrared repair of asphalt, comprising: at leastone blower operatively connected to a fuel supplying conduit; at leastone manifold, fixed to a frame, in communication with said fuelsupplying conduit; at least one converter in fuel communication withsaid manifold and having a plurality of downward facing slits throughwhich fuel can emerge and combust, the converter being positioned withinsaid frame; at least one reflector configured to reflect infraredradiation produced by the converter during combustion of said fueldownwardly; and at least one grid, made of infrared emitting material,configured such that a combustion chamber is formed between saidconverter and said grid, said grid further configured to absorb heatproduced in said combustion chamber and re-emit said heat downwardly inthe form of infrared radiation.
 2. The infrared asphalt heating andsoftening system of claim 1 wherein said downward facing slits of saidat least one converter are between approximately 0.4688″ and 0.5000″ inwidth.
 3. The infrared asphalt heating and softening system of claim 1wherein said downward facing slits of said at least one converter arebetween approximately 0.025″ and 0.035″ in thickness.
 4. The infraredasphalt heating and softening system of claim 1 wherein said downwardfacing slits of said at least one converter number 64 slits per 34″ ofconverter length.
 5. The infrared asphalt heating and softening systemof claim 1 wherein said converter is made of stainless steel.
 6. Theinfrared asphalt heating and softening system of claim 1 wherein saidconverter is cylindrical in shape.
 7. The infrared asphalt heating andsoftening system of claim 1 wherein said grid is made of nickelchromium.
 8. The infrared asphalt heating and softening system of claim1 wherein said at least one reflector is made of stainless steel.
 9. Theinfrared asphalt heating and softening system of claim 1 wherein a firstslit and a last slit are positioned approximately 1.250″ from opposingends of the converter.
 10. The infrared asphalt heating and softeningsystem of claim 1 wherein the plurality of downward facing slits areproduced using a milling machine.
 11. The infrared asphalt heating andsoftening system of claim 1 wherein the plurality of downward facingslits are produced using a band saw.
 12. The infrared asphalt heatingand softening system of claim 1 wherein the plurality of downward facingslits are produced using a laser.
 13. A method for infrared repair ofasphalt, comprising: providing an infrared asphalt heating and softeningsystem including at least one blower operatively connected to a fuelsupplying conduit, a manifold, fixed to a frame, in communication withsaid fuel supplying conduit, at least one converter in fuelcommunication with said manifold and having a plurality of downwardfacing slits through which the fuel can emerge and combust, theconverter being positioned within said frame, at least one reflectorconfigured to reflect infrared radiation produced by the converterdownwardly, toward asphalt to be repaired, and at least one grid, madeof infrared emitting material, configured to absorb heat produced bysaid converter and re-emit the heat toward said asphalt as infraredradiation; heating an area of said asphalt to be repaired using saidinfrared asphalt heating and softening system until said asphalt is softenough to be scarified using hand tools; scarifying and repositioningsaid asphalt; smoothing said asphalt; and adding fresh asphalt over saidsmoothed asphalt.
 14. The method of claim 13, further comprisingcompacting said fresh asphalt.
 15. The method of claim 14, wherein saidcompacting of said fresh asphalt is accomplished using a vibratorycompactor.
 16. The method of claim 14, wherein said compacting of saidfresh asphalt is accomplished using compaction equipment selected fromthe group consisting of paver screeds, steel wheel rollers, andpneumatic tire rollers.
 17. The method of claim 13, further comprisingadding maltenes to said heated and scarified asphalt prior to smoothingsaid asphalt.
 18. The method of claim 16, further comprising addingasphaltenes to said heated and scarified asphalt prior to smoothing saidasphalt.